This invention relates to a fuel supplying device for an internal combustion engine and more particularly to an improved device for operating an engine on a low quality fuel.
Because of the diminishing quantity of high quality fuels that are available for operating internal combustion engines, and the increased cost of such high quality fuels, it has been proposed to operate engines on fuels other than gasoline. For example, it has been proposed to operate an engine on fuels having lower quality than gasoline such as alcohol or kerosene. Kerosene is a commonly used fuel in connection with outboard motors. Where such lower quality fuels are used, however, it has been proposed to provide a system for introducing a higher quality fuel to the engine during certain running conditions such as starting, cold running and acceleration. Such "dual fuel engines" have fallen into one of two general categories. With one of these categories, the engine is provided with two separate induction systems, one for each fuel, and the operator can select which system supplies fuel to the engine for primarily all of its running conditions. Another type of system embodies a dual fuel charge forming device wherein the two different fuels are mixed with the air and introduced into the induction system in response to its running requirements. Such dual fuel systems of the types previously proposed have been very complicated and, furthermore, may present problems when running under some conditions. For example, with the type of device that automatically switches from one fuel to the other in response to the running conditions, there is a danger that the fuel transfer is not smooth during transitional conditions and unstable running may result.
It is, therefore, a principal object of this invention to provide an improved induction system and fuel supply system for an engine that permits it to operate with a low quality fuel.
It is a further object of this invention to provide a low quality fuel supply device for an internal combustion engine with a simplified arrangement for introducing a higher quality fuel at the operator's discretion or in response to certain running conditions.